Design Of Human-machine Interface For High Power Medium Frequency Inverting Resistance Welder

Resistance welder is widely used and developed in aerospace and other industries,because it is easy to operate and high efficiency. Digitized improve the quality of welding andbring computer based interactive interface to the welder. Operation of weld is more simple,intuitive and convenience. There are some unreasonable designs in the man-machine interfaceof weld in domestic and foreign markets. Aiming at high power medium frequency invertingresistance welder, this paper raises a design of man-machine interface with simple, intuitiveand flexible interface.The design selects PIC as the MCU, LCD as the display interface, keyboard as the inputdevice, RS232and SPI as the mean of communication between interface and lower computerby considering the functions to be achieved and other factors.According to the functional requirements determine the structure of the menu andimplement menu with tree structure. A doubly linked list and a structure array implementparent-child node and brother node respectively. Implement the functions of interface andhardware modules driver respectively. Since the kernel of μC/OS-Ⅱ is small and powerful,using it as a real-time operating system in this paper. The application is divided into eightseparate tasks with appropriate priority according to different functions. Synchronouscommunication between tasks relies on the semaphore. It implements effective scheduling ofmultitasking system and efficient completion of the man-machine interface. The tree structuremakes menu easy to modify. Different functions divided into independent tasks conducive tothe expansion of functions. It greatly increases the flexibility of the application system.A communication protocol is designed in order to guarantee reliable communicationbetween man-machine interface and lower computer. The protocol is consist ofcommunication type, packet format, definition of the command and data nature, data formatof the welding norms and current compensation. According to the sampling data, equallyselect some proper data points as interpolation nodes, using cubic spline interpolation toapproximate the actual welding specifications curve.